Durable, stiff finish for nylon and method for producing same



Patented Oct. 19, 1954 DUBABLE, STIFF FINISH FOR NYLON AND METHOD FOR PRODUCING SAME Albert C. Nuessle, Hatboro, and Russell F. Crawford, Philadelphia, Pa., assignors to Rohm & Haas Company, Philadelphia, Pa., a corporation of Delaware N Drawing. Application April 14, 1951, Serial No. 221,126

6 Claims. 1

This invention relates to a process for imparting to nylon yarns and fabrics a durable, stiff finish and to the resulting products.

stiffening of cotton and linen fabrics has long been brought about with the aid of starches and gums. Finishes of this type are not durable and are not generally applicable to nylon. Nylon has been treated with dispersions of polymeric resins to impart an improved hand, snag-resistance, greater body, and the like. But resin finishes for nylon fabrics have not heretofore provided a durable, stiff, crisp or papery finish which gives taffeta-like properties thereto.

There have been used for temporary sizing of nylon yarns, particularly for warp sizing, polymethacrylic acid and polyacrylic acid. As these are ordinarily used, they are scoured out after the nylon yarn has been woven or knitted into a fabric. During the time which yarns slashed with a polymethacrylic or polyacrylic acid solutions are heated for purposes of drying and at the temperatures ordinarily used, these finishes remain soluble and removable. When a nylon fabric has been treated with polymethacrylic acid and heated even at an unusually high temperature, for example, between 425 to 450 F., the sizing is still removable when the fabric is scoured. With polyacrylic acid, however, it has now been observed that at temperatures above those normally encountered in sizing there occurs some fixation of this sizing material, the fabric not returning completely to its original hand after ithe sized and heated fabric has been scoured. While for some purposes this type of finish is of definite interest, it is not truly permanent, may change with subsequent washing, and does not provide the extreme durability of finish which is imparted by the process of this invention.

It is an object of this invention to provide a method whereby nylon yarns and fabrics may be given a crisp, stiii finish. It is also an object of this invention to provide a durable, stiff finish for nylon yarns and fabrics.

It has been discovered that a crisp, stiff, durable finish is imparted to nylon yarns and fabrics by applying thereto an aqueous solution containing polyacrylic acid and a polyhydric alcohol and drying and heating the thus treated yarns and fabrics at an elevated temperature. Subsequent to these steps the treated yarns or fabrics may be washed with a mildly alkaline solution to neutralize excess acidity. The stiff finish is retained.

'Polyacrylic acids of a wide range of molecular sizes may be used. Molecular size may be empirically expressed in terms of the viscosity of aqueous solutions of acrylic acid. Preferred molecular sizes for purposes of this invention lie Within a. range in which a 5% aqueous solution of the polyacrylic acid gives a viscosity at F. from two to thirty centistokes with a range of two to twelve centistokes being particularly useful. Polymers of smaller molecular size can be used, but do not supply an economic stiffening action. size can also be used, but they suffer from several disadvantages, including difiiculties of handling a concentrate, diluting it, and applying solutions containing adequate solids for producing a strong, stiff finish.

As a polyhydric alcohol there may be used a glycol, such as ethylene glycol, propylene glycol, or diethylene glycol, glycerine, polyglycerine, pentaerythritol, dipentaerythritol, sorbitol, or mannitol. It is preferred that the polyhydric a1- cohol have not over six hydroxyl groups per molecule. Yet it has been found that polyvinyl alcohol can be used in conjunction with polyacrylic acid. Thus treated fabrics have a tendency, however, to become yellow and to discolor. The weight of polyhydric alcohol may desirably be varied from about 10% to about 100% of the weight of polyacrylic acid used. An excess of polyhydric alcohol over the above amounts may have a plasticizing action, decreasing the apparent stiffness from a fixed amount of polyacrylic acid. When a fabric with excess of polyhydric alcohol is washed, the plasticizing action disappears with removal of excess alcohol. If the fabric was processed at a relatively high temperature in the presence of excess polyhydric alcohol, a considerable change in the quality of the fabric may take place, for the alcohol at such a temperature may react with or attack the fiber substance, causing a fused effect or embrittlement.

The proportion of polyacrylic acid to polyhydric alcohol may be expressed in another Way. The ratio by weight of polyacrylic acid to polyhydric alcohol may be varied from about 10:1 to 10:10 with ratios from 10:2 to 10:5 being particularly desirable.

When mixtures having such ratios of reacting components are used, as small an amount of polyacrylic acid as one per cent with reference to the weight of the nylon produces a noticeable crispness. At 5% of polyacrylic acid the hand is quite stiff and with 10% the hand becomes boardy. The range of one to ten per cent of polyacrylic acid with reference to the weight of Polyacrylic acids of larger molecular nylon is a practical and effective one for all usual purposes where a crisp, stiff fabric is desired.

Solution containing polyacrylic acid and polyhydric alcohol is applied to nylon yarn or fabric by dipping, padding, or similar operation. Excess solution is wiped from or pressed out. of the fabric or yarn. The thus treated nylon is then dried and heated at a temperature between 300 F. and 450 F. for a time sufficient to render the sizing insoluble on the nylon. At 300 F. a curing time of at least 30 minutes and preferably 60 minutes is used. At 350 F. a curing time of about 10 minutes or more fixes the sizing materials on the nylon. At 375 F.. a curingtime of about two minutes accomplishes the desired result, while at 425 F. complete fixation of. sizing is brought about in a matter of about ten seconds. The range of 375 F. to 425 F. is a most useful one to give rapid setting of the coating materials. Longer periods of cure may, of course, be used and in some cases may be desirable'to bring about the full durability of the sizing. It is preferred that the temperature for effecting the fixation of polyacrylic acid and polyhydric alcohol be between 300 F. and 425 F. with times from 60 minutes down to ten seconds depending on the temperature.

After the sizing. has been insolubilized by heating, it is often desirable to remove any unreacted materials and/or to neutralize excess acidity. This is accomplished by Washing the cured nylon in a dilute solution containing an alkaline reagent, such as soda ash or ammonia. The thus washed yarn or fabric may be rinsed in water. It is then dried. The handleof the product is crisp, papery, and stiff. The product retains this handle even after being washed with a solution of an alkaline builder or with soap and builder solution at 120-160 F.

If the finish is applied after the nylon yarn or fabric has been dyed, little change in shade occurs, although in some cases the color appearsv somewhatmore intense due, without doubt, to an increased translucence. If the finish is applied before the nylon is dyed, the finish acts as a mordant for basic dyes and some acetate dyes. Light fastness of dyes is frequently im-- proved to a noticeable degree, depending on the dyestuif used. F

This, invention is illustrated by the following examples.

Example 1 A bathwas prepared with 1% of glycerine and 3% of a polyacrylic acid, which in-a 5% aqueous solution gave a viscosity of '5centistokes at 100 F; A nylon taffeta was-passed throughthebath A somewhat similar type of fabric madezof cellulose acetate was treated with the same bath and heated as above. The finish was not resistant to being washed in a hot soap solution.

Example 2 A dyed nylon marquisette was padded with a bath containing. of polyacrylic acid and 2% of glycerine. The padded marquisette showed a gain in weight of about 50% over the original.

weight of. the fabric. It wasdried and heated 4 for ten seconds at 425 F. It then had a stiff, crisp hand. There was a definite increase in the lightfastness of the dye. Treated fabric was subjected to ten washes at F. in a bath containing a commercial flaked soap. There was no appreciable change in hand.

A similar Orlon fabric was treated as above. The stiff finish was lost when the treated fabric was washed with a dilute soap and soda ash soution.

Example 3 A nylon lace was padded through a bath containing 3% of polyacrylic and 0.5% of pentaerythritol to give a pickup of about 50%. The lace was dried and heated at 350 F. for eight minutes. A stiff, durable finish resulted. Repeated washings in mild soap solutions did not change the hand.

Example 4 A sheer nylon fabric was padded through a bath containing 5% of polyacrylic acid and 3% of a polyglycerol. The fabric was dried and heated at 410 F. for 20 seconds. A crisp organdie finish resulted. It was quite durable under repeated washings in soap and soda solution.

Example .5

' A woven nylon fabric was passed through a bath containing 2% of glycerine and 6% of polyacrylic acid, a 5% solution of which had a viscosity at 100 F. of 18 centistokes. The fabric was squeezed between rolls, dried, and cured at 430 for 15 seconds. The finish was a stiff one, which was extremely wash fast. A wash test at 180 F. for 40 minutes in a solution containing 0.25% of soap and 0.25% of soda ash, followed by several rinses at F., did not change the hand.

The above procedure was repeated with substitution of polymethacrylic acid for polyacrylic acid. While an initial stiffness was obtained, this was lost during the wash test.

Example 6 A nylon taifeta was padded through a bath containing 10% of a polyacrylic acid and 7% of ethylene glycol. The taffeta was cured for two minutes at 370 F. It had a heavy, full'hand' which was durable, resisting removal in" alkaline soap solution.

Example 7' A sheer nylon fabric was passed throughv an aqueous bath containing 5% of a polyacrylic. acid (giving a viscosity to a 5% aqueous solutionof 12 centistokes at 100 F.) and 4% of sorbitol.. Excess solution was pressed out and the fabric.

was dried and heated at 400 F. for'45 seconds. A stiff, crisp organdie finish was obtained. It was durable and was not altered by several washes in 0.2% soap solution.

Example 8' siderable body and markedcrispness.

We claim:

1. A process for finishing nylon yarns and fabrics which comprises treating them with an aqueous solution containing 1 to of a polyacrylic acid and glycerine in an amount from about 10% to about 100% of the Weight of the polyacrylic acid and heating the thus treated nylon between 425 F. and 300 F. for a time of at least ten seconds up to about 60 minutes sufiicient to impart a finish resistant to soap solution.

2. A process for finishing nylon yarns and fabrics which comprises treating them with an aqueous solution of a polyacrylic acid at a concentration of about 1% to about 10% and a polyhydric alcohol in an amount of about 10% to about 100% of the Weight of said acid and heating the thus treated nylon between 425 F. and 300 F. for a time of at least ten seconds up to about 60 minutes sufficient to impart a finish resistant to soap solution.

3. A process for finishing nylon yarns and fabrics which comprises treating them with a solution containing 1% to 10% of a polyacrylic acid and a polyhydric alcohol in an amount from 10% to 100% of the polyacrylic acid and heating the treated nylon between 425 F. and 300 F. for a time from about ten seconds to about 60 minutes and sufiicient to insolubilize the treating materials thereon.

4. A process for finishing nylon yarns and fabrics which comprises treating them with an aqueous solution containing 1% to 10 of a polyacrylic acid and glycerine in an amount from 10% to 100% of the polyacrylic acid and heating the treated nylon between 425 F. and 300 F. for a time from about 10 seconds at the highest temperature to about minutes at the low temperature and sufificient to insolubilize the treating materials thereon.

5. Nylon fabrics and yarns having a crisp, stifi finish and carryinga sizing of an insoluble reaction product of polyacrylic acid, a polyhydric alcohol, and said nylon.

6. Nylon fabrics and yarns having a crisp, stifi finish and carrying a sizing of an insoluble reaction product of polyacrylic acid, glycerine, and said nylon.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,238,694 Graves Apr. 15, 1941 2,253,146 Spanagel Aug. 19, 1941 2,302,332 Leekley Nov. 17, 1942 2,343,095 Smith Feb. 29, 1944 2,406,779 Kurlychek Sept. 3, 1946 2,560,040 Whipple July 10, 1951 2,565,152 Wachter et a1 Aug. 21, 1951 2,568,760 Pearl Sept. 25, 1951 

1. A PROCESS FOR FINISHING NYLON YARNS AND FABRICS WHICH COMPRISES TREATING THEM WITH AN AQUEOUS SOLUTION CONTAINING 1% TO 10% OF POLYACYLIC ACID AND GLYCERINE IN AN AMOUNT FROM ABOUT 10% TO ABOUT 100% OF THE WEIGHT OF THE POLYACRYLIC ACID AND HEATING THE THUS TREATED NYLON BETWEEN 425* F. AND 300* F. FOR A TIME OF AT LEAST TEN SECONDS UP TO ABOUT 60 MINUTES SUFFCIENT TO IMPART A FINISH RESISTANT TO SOAP SOLUTION. 